Projecting apparatus and display system using same

ABSTRACT

Apparatus is described for projecting successive images onto a light-sensitive surface. The apparatus includes an evacuated enclosure and at least two movable electron-sensitive image storage areas therein. The areas are movable in a manner which permits storing on one area while, at the same time, the image stored on the other area is being projected onto the recording surface.

Waited States Patent Hamann [54] PROTECTING APPARATUS AND DISPLAY SYSTEMUSING SAME [72] Inventor: Omer F. lllamann, La Jolla, Calif.

[73] Assignee: Stromberg Datagraphix, Inc., San Diego,

Calif.

[22] Filed: May 18, 1970 21 Appl. No.2 38,403

[ Feb.29, 1972 3,155,451 11/1964 Dunster et al....

3,207,051 9/1965 Cooper et a1. ..95/4.5 3,258,525 6/1966 Piatt etal..... .346/1 10 X 3,359,563 12/1967 Stetten ..346/1 10 X 3,454,4147/1969 Andes et al.. 350/160 P X Primary Examiner-Samuel S. MatthewsAssistant ExaminerRicha rd M. Sheer Attorney-John R. Duncan [5 7]ABSTRACT Apparatus is described for projecting successive images onto alight-sensitive surface. The apparatus includes an evacuated enclosureand at least two movable electron-sensitive image storage areas therein.The areas are movable in a manner which permits storing on one areawhile, at the same time, the

image stored on the other area is being projected onto the recordingsurface.

4 Claims, 2 Drawing Figures 32 I6 38 Q I ELECTRONIC CONTROL SYSTEMMontani ..350/160 P UX PAIENTEDnaz-s m2 FIG.

ELECTRONIC CONTROL SYSTEM FIG. 2

INVENTOR. OMER F. HAMANN BY WW ATTORNEY PROJECTING APPARATUS AND DISPLAYSYSTEM USING SAME This invention relates to recording apparatus and,more particularly, to improved apparatus for projecting successiveimages onto a light-sensitive recording surface, and to an improveddisplay system utilizing such apparatus. The apparatus and system of thepresent invention are particularly useful in recording the output ofvarious types of computers in which information is stored.

Information retrieval systems employ various types of ap paratus andsystems for imaging the retrieved information, either temporarily orpermanently, on some type of display surface. The display surface may bethe screen of a cathoderay tube or the screen of a film projectionsystem, or may be pages of paper or similar material upon which theinformation is printed. Where information is retrieved from anelectronic store, a visible image is derived by application of thestored electrical signals to the deflection elements of a cathode-raywriting system to produce the information in the form of alphanumericcharacters, mathematical curves, or other convenient visible symbols.Various types of cathode-ray systems for accomplishing this are wellknown in the art.

Frequently, it is desirable to record information on films in which theinformation is of reduced size, such as in microfilm systems. Subsequentprojection of the image recorded on the film and enlargement thereofaffords a visual display of the retrieved information. Many films areavailable which are of sufficient sensitivity and resolution as topermit recordation by direct exposure to a typical electron-sensitivephosphor screen. Such films, however, usually have the disadvantage ofrequiring liquid chemicals for their development. Because of this,elaborate apparatus and long development time are often required, andtherefore such films may be inconvenient for use in systems in which ashort development time and simple development apparatus are desirable.

Certain types of films have been developed that require no additionalchemicals or special powders for image development. One such type offilm, sold under the name Kalvar and comprising a layer of thermoplasticresin having an ultraviolet-sensitive material dispersed therein, issensitive in the light spectrum from about 340t'o 430 millimicronswavelength in the ultraviolet spectrum. Other such types of filmsutilize photochromic materials or dyes which have the property of beingtransparent under normal conditions, but become temporarily opaque incertain regions of the visible light spectrum when stimulated withelectrons or ultraviolet light. The persistence of photochromic dyesremaining in the opaque state is primarily a function of theirtemperature and, therefore, images produced with such dyes may be erasedquickly by raising their temperature appropriately. Nevertheless, sometime is required for this process. Moreover, exposure of both Kalvar andphotochromic films to the image requires a relatively long length oftime or a very high level of intensity of the ultraviolet light.Although systems using optical fibers have been employed to transmitimages of visible light at high efficiency, where increased intensity isdesirable, such are not typically of advantage in exposing microimageson the types of films under consideration because the resolution islimited to the size of the fibers and because the fibers typically havelow transmissivity and high losses with ultraviolet light.

Thus, in construction apparatus for projecting successive images onto alight-responsive surface, numerous design problems may arise where thelight-responsive surface is subject to the limitations connected withKalvar" film or films utilizing photochromic dyes. Such apparatus shouldachieve adequate image intensity in the ultraviolet spectrum, and

should be capable of generating successive images at a rapid operatingrate even though the exposure of such a film to each image takes asubstantial length of time.

Accordingly, it is an object of the present invention to provideimproved apparatus for projecting successive images onto alight-responsive surface.

Another object of the invention is to provide an improved system inwhich such apparatus is employed.

A further object of the invention is to provide apparatus forfacilitating the recording of visual images of electronically storesinformation on film of a type that requires no additional chemicals orspecial powders for image development.

It is another object of the invention to provide apparatus of theforegoing type which is operable at a convenient rate of speed.

Other objects of the invention will become apparent to those skilled inthe art from the following description, taken in connection with theaccompanying drawings wherein:

FIG. 1 is a diagrammatical view of the system of the invention employingapparatus constructed in accordance with the invention;

FIG. 2 is a diagrammatical view of a portion of an alternativeembodiment of the system of the invention.

Very generally, the apparatus of the invention comprises an evacuatedenclosure 11, in which at least two movable image storage areas 12 and13 are disposed. Each area is sensitive to impingement of electronsthereon to produce an image in accordance with the pattern of electronimpingement thereon. Means 14 are also disposed within the evacuatedenclosure for directing electrons to impinge on a first one of the imagestorage areas in accordance with a predetermined pattern. A projectionsystem 16 is employed for projecting the image stored on a second one ofthe image storage areas onto a light sensitive surface 31. The firstimage storage area is movable from such position to enable projection ofthe image stored on the first image storage area.

Referring now more particularly to FIG. I, the evacuated enclosure 11may be any convenient structure of metal, glass or other suitablematerial. The illustrated shape is not critical to the invention,although the enclosure is shaped to include both image storage areas 12and 13. In this way no image storage material need be moved into or outof the vacuum system during operation of the apparatus. Moreover it isnecessary that the evacuated enclosure 11 enclose the electron-directingmeans 14 for proper operation thereof.

The electron-directing means 14 include an electron gun l7 and adeflection system 18. These items are shown schematically and may be ofa variety of types. Thus, the electrondirecting means 14 may operate tomove the electron beam in a manner to write lines of alphanumericcharacters or other symbols, or to produce the lines of an image rasterpattern. Alternatively, the beam may be deflected to a selected one of aplurality of shaped apertures in an opaque plate. The resulting crosssection of the beam defines a desired alphanumeric character or othersymbol and such character or symbol is produced upon impingement of thebeam on a target. The specific nature of the directing means 14 istherefore not critical to the invention.

An electronic control system 19 is provided connected to both theelectron gun l7 and the deflection system I8 to provide appropriateintensity and deflection signals in accordance with the information tobe reproduced. The control system 19 operates in accordance withelectronic information derived from an electronic information storagesystem, computer, or other source of information.

The image storage areas 12 and 13 are on a disc 21 of a suitabletransparent material, such as glass. The disc 21 has a thin coating 22of reversible (i.e., erasable) photochromic material or dyes. Also athin (e.g., 1 mil) layer 23 of phosphor is deposited over thephotochromic layer 22. The phosphor layer 23 is not necessary if thephotochromic layer 22 is sensitive to the impingement of electronsthereon. Many photochromic materials, however, are not sensitive toimpingement of electrons thereon and hence the layer of transparentphosphor 23 is deposited thereon to serve as an energy transducer. Thephosphor 23 becomes energized upon impingement of electrons to producethe necessary ultraviolet light output for causing the desired changesin the photochromic dyes of the layer 22. The size of the area 13 uponwhich the image produced by the electron-directing means 14 is formed isdependent upon the deflection characteristics and magnitude of thedeflection system I8, and the extremes of the image-defining beampattern are indicated by the dotted lines 24.

The disc 21 is mounted on a rotary axle 26 supported in a rotary motionfeed through bearing 28 supported in the wall of the evacuated enclosure11. The rotary motion feed through bearing 28 may be of any suitabledesign and construction, which permits rotation of the axle 26 whilemaintaining a vacuumtight seal between the axle and the wall of theenclosure 11. A satisfactory device for this purpose is Type No. 1324available from National Research Corp. The outer end of the axle 26 isdriven by a stepping motor 29 which is capable of being energized by theelectronic control system to rotate the disc 21 through a series ofdiscrete positions.

An image stored on the area 12 is projected on a light-sensitiverecording surface 31 by means of the projection system 16. Theprojection system 16 includes a flashlarnp 32 mounted exteriorly of theevacuated enclosure 11 andcontrolled by the electronic control system19. The flashlamp 32 produces a light output of high ultraviolet contentwhich is passed through a suitable window, not shown, in the wall of theevacuated enclosure 11. A dichroic mirror 33, capable of reflectingultraviolet light, is disposed in the path of the light from the lamp 32at an angle to reflect the light through the image storage area 12. Asuitable convergence lens 34 is positioned between the mirror 33 and theare 12 to effect optimum utilization of the light. After passing throughthe area 12, the light then passes'through a filter 35 which is designedto pass optical energy below about 430 millimicrons to restrict thelight energy to the range of sensitivity of Kalvar" film. The light ispassed through a focusing lens 37 to sharply image on thelight-sensitive surface 31. A suitable window, not shown, is provided inthe wall of the evacuated enclosure 11 to allow the light to passtherethrough.

In the recording system illustrated in FIG. 1, the lightresponsivesurface 31 comprises a portion of a strip of Kalvar film which is movedbetween two reels 38 and 39. Suecessive images are recorded on the filmin a latent condition and are subsequently developed, as is known in theart, by passing them through a heat developing station 41. Thus, aseries of microfilm images may be recorded on a strip of Kalvar film asit is passed from the reel 38 to the reel 39. Operation of the takeupreel 39 is controlled through a drive motor 42 by the electronic controlsystem 19.

After flash projection of the image on the area 12, the image is erasedby means of a lamp 43 which produces a light output of high infraredcontent. The lamp 43 is controlled by the electronic control system 19and passes its light through a suitable window, not shown, in the wallof the evacuated enclosure 11. As is known in the art, although thedichroic mirror 33 will reflect light of high ultraviolet content, itwill pass light of high infrared content. Accordingly, the infraredlight is passed through the dichroic mirror 33 to be concentrated by thelens 34 onto the area 12. This erases the images on the area 12, therebypreparing it for storage of a new image thereon. The filter 35 protectsthe surface 31 from the infrared light.

In operation, the stepping motor rotates to exchange the position of theareas 12 and 13. Although two image storage areas are referred to, thedevice is operable with not only two areas (with a step in the amount of180 rotation), but with more than two areas, depending upon the size ofthe disc in relation to the size of the individual areas. Moreover, the

- image storage areas need not be contiguous, nor need they be on thesame substrate. In the illustrated embodiment, exposure of one area canproceed simultaneously with projection and erasure of the other.Obviously, if three or more image storage areas are provided, theapparatus may be arranged so that exposure, projection and erasure canproceed simultaneously without'need for the spectral filter 35 and thedichroic mirror 33. In either case, exposure, erasure and projection canproceed simultaneously, which is a distinct advantage when photochromicmaterials are utilized, since erasure thereof and sometimes exposure canbe a slow process. No optical fibers are utilized to transmit the image,thereby avoiding the difficulties cased by resolution limitations andultraviolet losses inherent in optical fiber systems.

The phosphor employed in the layer 23 may be of any suitable type. Atype which emits light in the region of 360 to 400 millimicronswavelength is preferred. A l?l6 phosphor emits in this region. The eraselamp 43 is preferably of a type which provides energy in the region fromabout 400 millimicrons and higher in order to obtain photobleaching aswell as heat bleaching. Incandescent lamps emit in this region.Absorption characteristic data for' the various types of photochromicmaterial and Kalvar" films are available from manufacturers.

Referring now to FIG. 2, a modification of the display system of theinvention is shown that provides a visual display rather than simplyrecording information on film. A portion of a display system is shown inFIG. 2 in which only the lens 37 of the projecting apparatus of theinvention is illustrated. The display system includes a pair of rollers51 and 52, the latter being driven by a stepping motor 53. The rollers51 and 52 drive an endless belt 54 of photochromic film through anexposure station 56, a projection station 57 and an erase station 58.The erase station comprises a heater which erases images from the filmafter projection at the projection station. The photochromic film 54 isexposed at the exposure station 56 to produce a visual imagethereon. Aprojection system is provided including a projection lamp 59, a pair ofcondensing lenses 61, and a projection lens 63. A suitable mirror, notshown, folds the projection optics at the plane 62 and projects theimage through the projection lens 63 onto a display screen 64 upon whichthe information may be viewed. The motor 53 steps the film belt aroundso that subsequent images are displayed on the display screen 64.

It may therefore be seen that the invention provides improved apparatusfor projecting successive images onto a light-responsive surface. Theinvention also provides an improved system utilizing such apparatus. Theapparatus may be utilized for recording information on films of the typethat require no additional chemicals or special powders for imagedevelopment. Rapid production of successive images is accomplishednotwithstanding the fact that exposure of such films requiressubstantial amounts of light energy at ultraviolet wavelengths.

Various modifications of the invention in addition to those shown anddescribed herein will become apparent to those skilled in the art fromthe foregoing description and accompanying drawings. Such modificationsare intended to fall within the scope of the appendant claims.

What is claimed is:

1. Apparatus for projecting successive images onto anultraviolet-light-sen sitive sheet surface, comprising, an evacuatedenclosure, a movable member within said enclosure having at least twospaced image storage areas each comprising a transparent photochromicmaterial sensitive to impingement of electrons thereon to produce anopaque-and-transparent image in accordance with the pattern of electronimpingement thereon, means within said enclosure for directing electronsto impinge on a first one of said image storage areas in accordance witha predetermined pattern, a projection system for directing light of highultraviolet content through the image stored on a second one of saidimage storage areas onto a light-sensitive surface, means for movingsaid member to move said first image storage area to the position ofsaid second image storage area and to move said second image storagearea from such position to enable projection of the image stored on saidfirst image storage area and infrared from said first light sourcethrough said image to project the image, and wherein said erasing meanscomprise a second light source to produce light of high infrared contentlocated to pass light through said dichroic mirror to said image for 5erasing the image.

1. Apparatus for projecting successive images onto anultraviolet-light-sensitive sheet surface, comprising, an evacuatedenclosure, a movable member within said enclosure having at least twospaced image storage areas each comprising a transparent photochromicmaterial sensitive to impingement of electrons thereon to produce anopaque-and-transparent image in accordance with the pattern of electronimpingement thereon, means within said enclosure for directing electronsto impinge on a first one of said image storage areas in accordance witha predetermined pattern, a projection system for directing light of highultraviolet content through the image stored on a second one of saidimage storage areas onto a light-sensitive surface, means for movingsaid member to move said first image storage area to the position ofsaid second image storage area and to move said second image storagearea from such position to enable projection of the image stored on saidfirst image storage area and infrared radiation means to erase saidimage after projection.
 2. Apparatus according to claim 1 wherein saidmember is a rotary disc, and wherein said moving means are operable torotate said disc to move said image storage areas between saidpositions.
 3. Apparatus according to claim 1, wherein said projectionsystem includes a first light source to produce light of a highultraviolet content and a dichroic mirror for reflecting light from saidfirst light source through said image to project the image, and whereinsaid erasing means comprise a second light source to produce light ofhigh infrared content located to pass light through said dichroic mirrorto said image for erasing the image.
 4. Apparatus according to claim 1,wherein said projection system includes a light source of highultraviolet content, and said film comprises ultraviolet-sensitiveheat-developable vesicular film.